Sheet metal electrical baseboard heater



Sept. 22, 1964' E CLARKE METAL ELECTRICAL BASEBOARU HEATER Filed. New. 29, 1962 INVENTOR. WlLLlAM E. CLARKE.

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United States Patent 3,150,250 SHEET METAL ELECTRICAL BASEBOARD HEATER William E. Clarke, Cahokia, Ill., assignor to International Oil Burner Company, St. Louis, Mo., a corporation of Missouri Filed Nov. 29, 1962, Ser. No. 240,880 3 Claims. (Cl. 219341) This invention relates to the construction of electrical residential heaters of the type known as baseboard heaters, in which a fluid, usually water, circulates in a sealed tubular path.

.Heat exchanger units for other purposes have hereto fore been made by laying down patterns of a separating or weld-preventing substance, such as graphite, onto a surface of one sheet of ductile metal such as aluminum, then overlaying With a sheet of similar size, and then rolling the sheets together under great pressure. In this rolling the sheets are lengthened, widened and in effect welded together. Assuming that the graphite pattern has a portion whichcontinues to the edge of the sheets so welded together, or that the sheets are then sheared to provide an entrance to the pattern, fluid may be inserted to expand the pattern into a tubular chamber or passage.

It is not believed that any electrical baseboard heaters have heretofore utilized such a construction. In such heaters, a path of relatively small diameter tubing conventionally leads to a straight tube of substantially greater diameter in which an electrical heating element is accommodated, as in the patent to Reynolds, No. 2,772,342. The location of the heating element is conveniently at one side of the heater, so that it may be inserted endwise from the edge of the unit.

Although I have referred to expanding the pattern, actual stresses which occur on such expansion are relatively complex. If a readily distensible material were to be expanded from flat form in a plane to somewhat rounded form, such distension would be accompanied by displacement in the plane. Utilizing the rolled-together sheet construction, this displacement in the plane tends to be resisted by stresses in the welded-together portions of the sheets; If such stresses are applied unequally to the metal, as by expanding portions at one side of the sheet to greater diameter than adjacent portions, warping would tend to occur."

Another problem to be overcome is how to provide finned areas for radiation in such position as will promote the circulation of flow through the closed path. A third problemis to make optimum use of sheet material in squarely cut oblong sheets to constructa strong, com- In the present invention these problems are solved by utilizing two aluminum sheets in long oblong form, patterned with a weld-preventing material, rolled together and expanded, in which an integral hollow pocket, relativelyflat and enlarged along the plane of symmetry, is

providedin one end of the lower run of the'circulation path. In the pocketan electrical heating element of hairpinshape ismounted by an end cap at the side of the unit. An integral expansion tube extends into the broad upper marginal portion'of the unit, upward from the circulation pattern and at the side of the oblong opposite the pocketfi The remainder of thisbr'oad marginal portion is utilized for cooling, by slotting and bending 3,150,250 Patented Sept. 22, 1964 so as to provide transverse integral fins with slots alternating between them. Being directly above that portion of the upper run which receives the circulating flow directly from the heater element pocket, maximum cooling effect is afforded. Similarly formed fins may also be provided in other available areas of the oblong unit.

These results and others which will be apparent from this specification are achieved in the embodiment shown in the accompanying drawings, in which:

FIGURE 1 is a side view, partly in perspective, of an electrical baseboard heater unit embodying the present invention.

FIGURE 2 is a sectional view taken along line 22 of FIGURE 1, and somewhat enlarged.

Referring now to FIGURE 1, the oblong form of the baseboard heater is shown. The cross-sectional view FIG- URE 2 shows the general symmetry of its construction, except for its cooling fins hereinafter referred to. Symmetry in the expansion of the closed tubular path from the plane aa is readily obtained by the utilization of two oblong aluminum sheets 11 and 12 of equal thickness restrained in the expansion process to the expanded width shown in FIGUREZ. Either by selecting slightly different thicknesses or by procedures limiting expansion unequally, symmetry in expansion could be avoided if desired, but this would here offer no advantage. The fact that the fins described hereinafter are formed to one side only of the plane a-a as shown in the drawings, is not to be taken as inconsistent with the generally descriptive reference to such plane as one of symmetry.

The welding together of the sheets 11, 12 by the rolling process so unites portions of them along the plane aa to give a general fiat shape to the oblong heater unit. The tubular path expanded outward from the plane aa has several portions which may be separately identified as herein described. A substantially horizontal lower passage or run 13 extends from the right side of the unit, and at its left end it joins a portion of greater extent along the plane of symmetry, this latter portion beingreferred to as the pocket portion 14. The pocket portion 14 extends to the left edge of the oblong unit,

as shown in FIGURE 1, to permit insertion of an electrical heater unit as shown in that figure. Connecting upward from the pocket portion 14 is a flow exit curved path portion 15, which connects integrally with a substantially horizontal upper passage or run 16, preferably of similar cross-section to that of the lower run 13. The upper'run 16 extends almost to the right end of the oblong and there connects with both a downward-curved pared to the'upper run 16; it is limited to the right side of the oblong, diagonally opposite the pocket portion 14; and itterminates in the upper edge of the margin 20. After. filling the necessary amount of water into the unit,

this upper edge margin 20 is crimped closed by revers ing the curvature of one of the sheet portions to concave,

it thus forming the upper edge crimp 21, which is then sealed as by heliarc welding.

The pocket portion 14 is of sufiicient extent, measured along the plane aa, to accommodate a hairpin-shaped electrical heating element generally designated 25, of conventional construction and insulated within a metal sheath, as shown inFIGURE 2. Such heating element is actually in the shape of a U turned sideward, whose ends are electric terminals 26, to which conventional connectors, not shown, connect the heating element 25 to a source of electrical power. The terminal ends 26 support the heating element spacedly within the pocket '14 in the position shown in FIGURE 1. This support is effected by a symmetrical side edge crimp 27 as shown in FIG- URE l, which is sealed by heliarc welding. The slenderness of such electrical hairpin-shaped heater element permits it to be aligned with the plane aa and accommodated within the relatively fiat pocket 14. Since the runs 13 and 16 and the pocket ld are preferably expanded to the same Width, the expansion causes little warping of the unit out of its fiat oblong shape.

Flat areas remaining along the plane of symmetry, not needed for strength and sealing, areutilized for cooling fins. An area which calls for cooling is'the portion at the left side above the heater pocket 14. The water heated in the pocket 14 tends to flow directly upward through the flow exit passage portion 15, and circulates as shown by the arrows in FIGURE 1. It should be cooled promptly to the greatest extent possible, both for efficient heat transfer and for best flow circulation. By locating the expansion tube portion 19 at the right side, the entire left side area of the margin 20 above the upper run 16 is available for integral fins to carry away heat from this portion of the circulation path. Pins 39 are formed by piercing and bending planar, welded-together areas of the roll-welded sheets 11, 12 not expanded outward from the central .plane a-a. Conveniently the fins 36 are formed to one side only'of the plane a-a leaving alternating slots 31. S

completely are the sheets 11, 12 united by the roll welding process that they are in all practical respects a unitary sheet. For this reason the edges of the fins 30 are shown in FIGURE 1 as single edges; and in the cross sectional view, FIGURE 2, the line which divides the sheet 11 from the sheet 12 is shown as a phantom line. Areas in which fins 30 are so formed include the upper fin area 32 in the margin 20 occupying nearly the entire area to the left edge of the expansion tube 19.

Preferably, there are additional finned areas, including give it integral structural "strength, much likethat of an I-beam, as will-be apparentfrom the cross-sectional view, FIGURE 2. As a result the unit is capable of withstanding rough handling, as in transit, without damage or the likelihood of leakage. A

As a final familiar manufacturing step, the passageway portions except the expansion tube 19 are filled with water or'other circulating fluid; the pocket portion 14 is closed by the side edge" crimp 27 which holds the hairpinshaped heater unit 25, and the upper endof the .expanr si'on tube portion 19 is closed bylthe' upper edge crirnp 21 and 'boththe crimps 21, 27 are welded. An electrical outlet boxsupplying the connectors '27 ,with power maybe attachedin the conventional manner, and thermo static or other controls added. The unit maythcn be mounted in suitable ornamentalenclosure as'willpermit the flow of convection air for use as a baseboard heater in the conventional manner.

By the construction described, maximum used is made of the oblong pattern. An efficient heater pocket, suitable for the hairpin-shaped heater unit is provided, as is an integral expansion tube, without warping the sheets from the optimum oblong pattern. A finned cooling provision is made in the locations which best promote circulation of the water. The integral unit has strength and sturdiness which far surpasses baseboard heaters made heretotore by. joining separate pieces and components and mounting them in a support.

Modifications of the invention from the specific embodiments shown may be made without departing from the scope of the invention, which is to be taken as fully coextensive with the claims hereof.

I claim:

1. An electrical baseboard hearter, comprising two sheets having portions united to each other along 7 a plane, said sheets having portions extending away from the plane in a pattern to form a self-contained, sealed tubular path having a lower substantially horizontal run,

an upper substantially horizontal run, and

curved end portions connecting said upper and lower runs whereby to provide a self-contained, sealed path' for circulating flowof a fluid therein,

an integral expansion tube communicating with and extending from the sealed path of circulating flow, said lower run having at its oneiend an enlarged pocket portion, together with a fluid contained within said path, and

an electrical heating element within the pocket portion,

said heating element having electrical terminal ends which spacedly support said element within the path of circulating now through the pocket. 2. An electrical baseboard heater, comprising two oblong sheets having portions united to each other along a'plane of symmetry, V g said sheets having portions extending" symmetrically away from the plane of symmetry ina patternforrriing a tubular path having v a lower substantially horizontal run, an upper substantially horizontal run, and I curved end portions connecting said upper and lower runs whereby to provide a path for circulating flow of a fluid therein, 7 said sheets having a margin portion above said upper run, said margin portion containing at one'side of the oblong an inner expansion tube in communication with and extending from the path of'circulating fluid flow, j' said'lower run having a portion at its is of greater extent. along the plane of symmetry than the'remainder of said path whereby to provide a hollow relatively flat pocket, together with V a'fluid contained within said path, and

a hairpin-shaped electrical heating element within the pocket, said heating element having electrical terminal ends which spacedly support said element pathjof circulating flow through the 7 within "the pocket. f V g 3. An electrical baseboard heater, comprisingv two oblong sheets havingportions united to each other along a plane,

1 gsaid sheets having portions extending away from the plane in a pattern forming a tubular path having a lower substantiallyhorizontally-extending run, an upper substantially horizontally-extending run, and curved end portigns connecting saidupp'er and. lower Qruns whereby'to provide a path for; circulating flow of a fluid therein, 1 F

7 said oblong sheets further having a marginjportion one end which above the upper run, said margin portion containing at one side of the oblong an upward extension from the path of circulating flow and an integral expansion tube,

said margin portion adjacent to said integral expansion tube and extending to the opposite side of the oblong having integral cooling fins extending transverse to the plane and slots alternating between the fins,

said lower run having a portion extending to one end of the oblong, said lower run portion being of greater extent along the planethan the remainder of said path whereby to provide a hollow relatively flat pocket,

together with a fluid contained within said path, and

a hairpin-shaped electrical heating element within said flat pocket and having electrical terminal ends by which the heating element is supported spacedly within the path of circulating flow through the pocket.

References Cited in the file of this patent UNITED STATES PATENTS Ogilvie Oct. 14, 1930 Hurley May 30, 1944 Reynolds et al. Nov. 27, 1956 Heuer et a1 Feb. 4, 1961 Manning July 4, 1961 Heuer et al. July 31, 1962 Notice of Adverse Decision in Interference In Interference No. 95,108 involving Patent No. 3,150,250, W. E. Clarke, SHEET METAL ELECTRICAL BASEBOARD HEATER, final judgment adverse to the patentee Was rendered May 27, 1968, as to claims 1 and 2.

[Ofliaz'al Gazette December 17, 1.968.]

Notice of Adverse Decision in Interference In Interference No. 95,108 involving Patent No. 3,150,250, IV. E. Clarke, SHEET METAL ELECTRICAL BASEBOARD HEATER, final judgment adverse to the patentee was rendered May 27, 1968, as to claims 1 and 2.

[Ofiiez'al Gazette December 1'7, 1.968.] 

1. AN ELECTRICAL BASEBOARD HEARTER, COMPRISING TWO SHEETS HAVING PORTIONS UNITED TO EACH OTHER ALONG A PLANE, SAID SHEETS HAVING PORTIONS EXTENDING AWAY FROM THE PLANE IN A PATTERN TO FORM A SELF-CONTAINED, SEALED TUBULAR PATH HAVING A LOWER SUBSTANTIALLY HORIZONTAL RUN, AN UPPER SUBSTANTIALLY HORIZONTAL RUN, AND CURVED END PORTIONS CONNECTING SAID UPPER AND LOWER RUNS WHEREBY TO PROVIDE A SELF-CONTAINED, SEALED PATH FOR CIRCULATING FLOW OF A FLUID THEREIN, AN INTEGRAL EXPANSION TUBE COMMUNICATING WITH AND EXTENDING FROM THE SEALED PATH OF CIRCULATING FLOW, SAID LOWER RUN HAVING AT ITS ONE END AN ENLARGED POCKET PORTION, TOGETHER WITH A FLUID CONTAINED WITHIN SAID PATH, AND AN ELECTRICAL HEATING ELEMENT WITHIN THE POCKET PORTION, SAID HEATING ELEMENT HAVING ELECTRICAL TERMINAL ENDS WHICH SPACEDLY SUPPORT SAID ELEMENT WITHIN THE PATH OF CIRCULATING FLOW THROUGH THE POCKET. 